About 15 years ago, a friend of mine—let’s call him Peter—bought a house in a coastal town north of San Francisco. The house is on a cliff overlooking the Pacific. The location is spectacular. Ospreys commute past it, carrying fish for breakfast. The steady background noise of waves on the beach is interrupted by the strange cries of seals. The view of the Pacific changes with the season, and with the vagaries of light and weather. The view is never the same. It is always beautiful.

That physical beauty is why Peter and his wife bought the house. They made a bet. The bet was that they’d be able to enjoy the house for the rest of their lives. As a climate scientist, Peter understood that the gradual erosion of the cliff’s edge would be exacerbated by human-caused increases in sea level. The risk was visibly evident. A neighboring house closer to the cliff’s edge was already partly suspended over the void, awaiting the inevitable transition from the horizontal to the vertical.

Having seen the view from the house on the cliff, watched the ospreys, and listened to the seals, Peter and his wife took a risk that seems acceptable. We all need things of beauty in our lives.

Erosion does not gnaw away at their cliff at exactly the same rate each month, each season and each year. Heavy rains affect the stability of the cliff’s soil. High tides and large waves can take big bites out of the beach protecting the cliff. Given the complexity of erosion, it’s not possible to make a confident prediction about the lifetime of the house. But one prediction can be made with absolute certainty. Human activities are warming the world’s oceans, raising sea levels and bringing the Pacific Ocean closer to Peter’s front door.

Over the past year, the United States has witnessed a different kind of erosion. There has been an erosion of our democratic norms and institutions, with attacks on the legitimacy of courts and judges, the professionalism and integrity of intelligence agencies, and the fairness and patriotism of the press. Protections on clean air, clean water and human health are crumbling before our eyes. The boundaries of our national parks are eroding. The borders between what is real and what is imaginary are eroding, caving in to the relentless assault of “alternative facts,” outright lies and declared reality. Civility and decency are eroding on a daily basis, undercut and weakened by language emanating from the White House.

Trust is eroding. The rest of the world no longer trusts our word. They no longer believe that the United States is committed to solving the problem of global warming—a problem for which our country bears primary responsibility. Trust in our fellow citizens is being eaten away, undermined by the rhetoric of fear, of otherness, of “American carnage.” And trust in our political systems is eroding: achieving desired political ends seems to justify any means, and any meanness.

In the political world, as in the physical world, erosion creeps up on you. One day the United States is signing the Paris climate accord, part of the community of nations working to ensure the long-term habitability of this planet. A year later our country is alone, isolated, mistrusted, mocked for the ignorance and irrationality of our leaders. We are an object of pity and concern. Other countries witness this erosion of our centuries-old democracy, and wonder how close the United States is to the cliff.

Peter and his wife had to decide whether they were comfortable living with coastal erosion. Soon, we must all decide whether we are comfortable living with a very different kind of erosion, which threatens something far more important than our houses—who we are, what we value, and what type of world our descendants will inherit.